Smarty - Smarty provides address validation, autocomplete, geocoding and reverse geocoding services covering addresses in over 240+ countries.
Loqate - The Standard in Global Address Verification
Addressy - Addressy is address verification software that captures and verifies addresses on websites.
Melissa Data Quality - Melissa helps companies to harness Big Data, legacy data, and people data (names, addresses, phone numbers, and emails).
Addressify - Addressify is an API that allows developers to implement address verification, validation and autocomplete for Australia in their apps.
AddressZen - Effortless Address Lookup.